Husky 353 - help with homemade port job

[hokiebob]

Hello-I'm new here but have been a casual reader for a while.  I have a question about my Husky 353.  I've done a muffler mod and retuned the carb, but am not wondering about a port job.  I've done my fair share of hotrodding, but chainsaw/2 stroke hotrodding is new to me.  I know there must be lots of theory and know-how in porting 2 strokes, but I'm after something that carries a good powerband but cuts quickly and is durable.  I want a saw that is reliable but "gets is done".

Where would one start?  From my reading, it appears that removing the base gasket will up the compression ratio slightly and also change the port locations slightly (lower them although I'm not sure the best way to seal it), but I don't really understand the mechanics of opening or moving the ports. 

Can anyone offer some advice?

thanks again, I really enjoy reading this forum--there's lots of smarts here!

[jokers]

...........I have a question about my Husky 353.  I've done a muffler mod and retuned the carb, but am not wondering about a port job.  I've done my fair share of hotrodding, but chainsaw/2 stroke hotrodding is new to me.  I know there must be lots of theory and know-how in porting 2 strokes, but I'm after something that carries a good powerband but cuts quickly and is durable.  I want a saw that is reliable but "gets is done".

Where would one start?  From my reading, it appears that removing the base gasket will up the compression ratio slightly and also change the port locations slightly (lower them although I'm not sure the best way to seal it), but I don't really understand the mechanics of opening or moving the ports. 
Can anyone offer some advice? 

Yeah, don`t do it until you understand what causes what, don`t take anyone`s generic advise that removing the base gasket and a millimeter here or there will achieve what you want without having a solid grasp of what each action should accomplish. Consider that port time area, whether achieved through the use of a camshaft or piston porting is essentially the same and that it`s all moot if the intake is insufficient. You have already addressed the exhaust but for the ultimate enhancement you would factor it into the final build because after all is said and done, engines are pumps right? Then you can consider the ignition.

Performance advice that I give to most people before suggesting any mod is to really learn how to sharpen a chain. First, sharp chain will make most saws cut like a different machine. Second, less than sharp chain will not allow the full potential of a powerful saw to be appreciated.

I`m sorry Bob but I consider your questions to be outside the normal realm of this forum, there are others better suited to the knowledge that you seek and given that all of the info you should have before starting is already out there, I don`t feel that you would be adequately educated in one thread.

[JimBuis]

Hokiebob,
I essentially agree with Jokers. Grinding the ports on a 2 stroke without an intimate understanding of what each modification will do is like someone taking the camshaft out of their car and grinding on it while blindfolded. If you modify the ports on a 2 stroke and make a mistake, it is extraordinarily difficult to undo it. A serious error might ruin the engine entirely.

IMHO,
Jim

[SawTroll]

Can anyone offer some advice?!

Yes, send the saw to Ed Heard for a woods mod job!   

[hokiebob]

Gee, thanks for the advice, though it seems a bit harsh Jokers.  I understand chain sharpening/grinding--not perfect at it but I can do it pretty well.  I've seen many threads in here regarding similar questions and there seem to be lots of info sharing.  All engines are not created equally, I understand that, but concepts can carry between stihl/husky/jred, etc.

Clearly its not as simple as grinding this out and its 5 hp--everything works together--fueling, airflow, ignition, etc.  I was just curious if there were "rules of thumb" regarding this....similar to opening up muffler outlets to ~85% of exhaust port opening helps the saw out--85% is debatable, but nonetheless, its directionally correct.

thanks for any help
bob

[Tony_T]

I've ported a fair number of two stroke motocross cycles. 

Things that will help with no danger of screwing things up is: 1) to polish the exhaust port to a mirror finish, will increase flow by removing casting marks and prevent buildup of carbon in the port.  2) You can touch up the transfer ports the same way but they don't need to be mirror smooth.  3) If you have the bottom end apart polish the insides of the cases same as the transfer ports (yes gasses flow through here too). 4) Check that intake/exhaust flanges line up well and no gaskets hang out into the ports.

Do this by hand with some emery cloth, don't use the dremel and start changing the shape/size of the ports.......

Sometimes the intake is best left rough as some turbulence helps atomization of the incoming fuel charge; depends on tyhe engine. 

None of the above changes port timing (e.g. true porting which effects port timing) but will help increase flow without the chance of any deleterious mistakes and should not effect the usable RPM range (up or down) of the saw.

[hokiebob]

Thanks Tony.  Thats what I'm after--sounds much like porting/polishing Big Block Chevy's (roucher intakes for atomization, gasket matching manifolds, polishing, etc.).  I'll admit that my understanding of 2 strokes is much weaker than of 4 strokes, hence my questions here.  I've not measured the base gasket and don't have an idea what it does to compression ratio but it's likely noticable, but will likely increase temps and need increased fueling/ignition.

Again, I'm just curious directionally which way things need to move.

thanks again, Tony.
b

[Tony_T]

One more thing.  Check that the base gasket also lines up well with transfer ports/bottom end, if needed trim it to fit. 

[ehp]

the 353 is a very low port motor so to get it running good you need to do alot of porting, the transfers ports have doors on them like the 359 so there are huge blockages in the path that need to be worked on, this is one motor where the porting guy earns his money cause you remove alot more metal than most motors